Open-Cell Foam Sheet for Anisotropic Adhesion
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Solution Overview
Problem
Existing adsorption temporary fixing sheets, particularly silicone foam sheets, fail to provide sufficient shear adhesive strength in a direction parallel to their surface while maintaining weak adhesive strength in a direction vertical to the surface, which is essential for applications requiring lateral fixation and easy peeling, especially in high-temperature and low-temperature environments.
Innovation Solution
A foam layer with an open-cell structure is developed, where the silicon chip vertical adhesive strength is kept low compared to the silicon chip shearing adhesive strength across various temperatures, ensuring strong lateral adhesion without excessive vertical adhesion. This is achieved through a specific resin composition and curing process, including the use of a silicone resin foam with controlled cell structure and surface roughness, allowing for easy peeling without adhesive residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicone foam sheet is used as an adsorption temporary fixing sheet, then heat resistance and weatherability are improved, but shear adhesive strength in a direction parallel to the surface is insufficient
Solution Approach 1:
The patent changes the physical and chemical parameters of the foam material by controlling the cell structure (open-cell vs closed-cell ratio), cell size distribution, and wall thickness to achieve the desired balance between heat resistance and shear adhesive strength. The foam density and surface roughness are also optimized to enhance lateral adhesion while maintaining thermal stability.
Solution Approach 2:
The patent employs composite foam structures combining different cell types (open and closed cells) in specific ratios, and may incorporate surface treatments or coatings to create a composite material that exhibits both heat resistance and improved shear adhesive properties that neither component alone could achieve.
2Strength
If adhesive strength is increased for firm fixation, then lateral adhesion is improved, but peeling becomes difficult
Solution Approach 1:
The patent applies different adhesive characteristics to different directions by optimizing the foam's anisotropic structure. The cell wall orientation, density gradient, or surface treatment creates direction-dependent adhesion: strong lateral bonding through interlocking cell structures, but weak vertical bonding allowing easy peeling when force is applied perpendicular to the surface.
Solution Approach 2:
The foam structure is designed to exhibit dynamic adhesive behavior where the bond strength responds differently to lateral versus vertical forces. The open-cell structure allows deformation under lateral stress to maintain strong bonding, while permitting clean separation under vertical peeling forces.
3Ease of operation
If a pressure-sensitive adhesive tape is used for temporary fixing, then ease of application is improved, but adhesive residue and substrate breakage occur at high temperatures
Solution Approach 1:
The foam tape is designed as a single-use temporary fixing material that can be applied and removed without leaving residue. The foam structure itself serves as the adhesive medium rather than relying on separate adhesive layers, allowing clean disposal or removal after the temporary fixing function is completed.
4Strength
If heating is applied to increase peel strength, then adhesive bonding is improved, but substrate breakage and adhesive residue increase
Solution Approach 1:
The patent optimizes the foam's thermal and mechanical parameters including cell structure, density, and material composition to achieve adequate peel strength at lower temperatures. The controlled cell morphology allows the foam to maintain structural integrity and adhesive performance without requiring high-temperature processing that would cause substrate damage or adhesive degradation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The open-cell structure foam layer provides a sufficient shear adhesive strength in a direction parallel to the surface while maintaining a weak adhesive strength in a direction vertical to the surface, ensuring effective temporary fixing and easy peeling across a wide temperature range without adhesive residue, making it suitable for various industrial applications.
Implementation Method 1
A foam sheet having adsorptivity has heretofore been used as, for example, a sheet for preventing the overturning or slippage of furniture or home electric appliances
Data Source
AI summary
Provided is an adsorption temporary fixing sheet having a sufficient shear adhesive strength in a direction parallel to its surface, and having a weak adhesive strength in a direction vertical to the surface. Also provided is a method of producing such adsorption temporary fixing sheet. The adsorption temporary fixing sheet includes a foam layer including an open-cell structure, wherein, when a silicon chip vertical adhesive strength of a surface of the foam layer after 20 hours at each of such different temperatures as −40° C., 23° C., or 125° C. is represented by V1 (N/1 cm□), V2 (N/1 cm□), or V3 (N/1 cm□) and when a silicon chip shearing adhesive strength of the surface of the foam layer after 20 hours at each of the different temperatures (−40° C., 23° C., or 125° C.) is represented by H1 (N/1 cm□), H2 (N/1 cm□), or H3 (N/1 cm□), relationships of V1<H1, V2<H2, and V3<H3 are satisfied.